Abstract
The relationship between the changes in forward head posture (FHP), neck mobility and headache parameters was analysed in 25 patients with chronic tension-type headache (CTTH) undergoing a physical therapy programme. Side-view pictures were taken to measure the cranio-vertebral angle in the sitting and standing positions. A cervical goniometer was employed to measure the range of all cervical motions. A headache diary was kept to assess headache intensity, frequency and duration. All patients received six sessions of physical therapy over 3 weeks. Outcomes were assessed at baseline, after treatment and 1 month later. Neck mobility and headache parameters showed a significant improvement after the intervention, whereas posture changes did not reach statistical significance. No correlations were found between FHP, neck mobility and headache parameters at any stage. Changes in these outcomes throughout the study were not correlated either. FHP and neck mobility appear not to be related to headache intensity, duration or frequency in patients suffering from CTTH. Although patients showed a reduction in the range of motion in the neck, it is uncertain whether this is consistent with TTH.
Introduction
Tension-type headache (TTH) is the most frequent headache in adults. Population-based studies indicate 1-year prevalence rates of 38.3% for episodic TTH and 2.2% for chronic TTH (CTTH) (1). Cervical musculoskeletal abnormalities are usually linked to TTH (2). One of the most common cervical dysfunctions is an excessive forward head position or forward head posture (FHP), which has already been related to several headache disorders, e.g. cervicogenic headache (3) and postconcussional headache (4). Restricted neck mobility has also been found in some headaches, e.g. cervicogenic headache (5). Scientific data referring to neck mobility and FHP in TTH are scarce. Marcus et al. have reported that patients with TTH had more posture abnormalities, including FHP, than healthy subjects (6). On the other hand, Zwart found no significant difference in neck mobility between TTH patients and healthy control subjects (7).
We have recently reported that a group of patients with CTTH showed greater FHP and lesser neck mobility than healthy controls. In the CTTH group a negative correlation was found between the cranio-vertebral angle and headache frequency, so that a greater FHP was associated with a higher frequency of headache. Conversely, headache intensity and headache duration were not correlated with FHP. Otherwise, neck mobility did not correlate with any of the assessed headache parameters (8). In order to shed light on the potential role of both musculoskeletal abnormalities in the clinical course of TTH, we assessed a group of CTTH patients throughout a physical therapy programme. Specifically, we analysed the relationship between the changes in FHP, neck mobility and several clinical variables and the intensity and temporal profile of headache.
Materials and methods
Subjects
Twenty-five patients suffering from CTTH participated in this study from April 2004 to June 2005. Patients were diagnosed by an experienced neurologist according to the criteria of the International Headache Society (IHS) (9). Key elements of headache history were ascertained, including family history, headache features, temporal profile and present and past medications. None of the patients fulfilled current criteria for other primary headaches. To be included, patients had to describe all the characteristics typical of TTH: bilateral location, pressing and tightening pain, mild or moderate intensity [no more than 7 on a 10-cm visual analogue scale (VAS)], and lack of aggravation during routine physical activity; none of them reported photophobia, phonophobia, vomiting or evident nausea during headache. All cases had evolved from episodic TTH, but had to have headache on at least 15 days per month for >3 months to be considered chronic. A headache diary was kept during the first 4 weeks in order to substantiate the diagnosis (10). Medication-overuse headache as defined by the IHS (9) was ruled out in all cases. Otherwise, there were no indications of other secondary headaches by history, physical or neurological examination, or appropriate tests including neuroimaging (computed tomography or magnetic resonance imaging). The health status of all participants was clinically stable, without any evidence of other concomitant chronic disease.
This study was supervised by the Departments of Physical Therapy and Neurology of Rey Juan Carlos University and Fundación Hospital Alcorcón, Spain, and was also approved by the local ethics committee. All subjects signed an informed consent form prior to inclusion.
Forward head posture assessment
A picture of the lateral view of each subject was taken to assess FHP objectively. The base of the camera was set at the height of the subject's shoulder. The tragus of the ear was clearly marked and a plastic pointer was taped to the skin overlying the spinous process of the seventh cervical vertebra (C7). Once the picture was obtained, it was used to measure the cranio-vertebral angle, i.e. the angle between the horizontal line passing through C7 and a line extending from the tragus of the ear to C7 (Fig. 1) (11, 12). A smaller cranio-vertebral angle indicated a greater FHP. Raine and Twomey (13) have reported the reliability of this procedure as high [intraclass correlation(ICC) = 0.88]. In each evaluation, head posture was assessed in both the sitting and standing positions.
Measurement of the cranio-vertebral angle. The angle was assessed directly from a side-view picture using a protractor image and a straight edge.
Neck mobility assessment
Neck mobility was assessed by means of a cervical goniometric device manufactured by Performance Attainment Associates (St Paul, MN, USA). The cervical goniometer has already obtained an intratester reliability (ICC) ranging from 0.7 to 0.9 and an intertester reliability (ICC) ranging from 0.8 to 0.87 (14, 15). The extent of motion for each movement of the neck in a single direction was measured. For this purpose, all subjects were asked to sit comfortably on a chair and the goniometer was placed on top of the head. Once the goniometer was set in neutral position, they were asked to move the head as far as possible in a standard way: forwards (flexion), backwards (extension), right lateral flexion, left lateral flexion, right rotation and left rotation. Two measurements were made sequentially by the same assessor and recorded for each type of movement. Since no significant differences were found between the two measurements (ICC ranging from 0.9 to 0.94), the mean was employed in further statistical analysis. The protocol for the assessment of both FHP and neck mobility has been described in detail elsewhere (8).
Physical therapy programme
All patients received six sessions of physical therapy over 3 weeks (two sessions per week) with a physical therapist experienced in the management of headache disorders. Thus far, the Cochrane Pain, Palliative Care and Supportive Care Group has found no rigorous evidence for the effectiveness of different therapeutic programmes in the management of TTH, although spinal manipulation has appeared superior to drug therapy by providing a sustained short-term effect (16). On the other hand, a recent systematic review of manual therapies in TTH has found inconclusive evidence of effectiveness (level 4) for spinal manipulative therapy, and limited evidence (level 3) for soft tissue techniques (17). As it is not yet known which particular physical therapy programme is most effective for TTH, we applied both spinal manipulation/mobilization focused on the cervical and thoracic spine (18), and manual treatment of pericranial muscles (temporalis, suboccipital, upper trapezius, sternocleidomastoid and semispinalis muscle) (19). Different manual therapy approaches, such as pressure release technique (20) or muscle energy techniques (21), were applied to these muscles. In addition, patients were asked to perform ergonomic exercises aimed at postural corrections of the head and the neck.
Study protocol
We used a prospective A1–B–A2 design. Phase A1 (preintervention phase) consisted of a 4-week baseline period when no intervention was made. Phase B (intervention phase) was the 3-week treatment period through which patients were treated with the above-mentioned programme of physical therapy. Phase A2 (post-intervention phase) was a 5-week post-intervention period. All patients had three measuring appointments: 1, pretreatment (first visit, week 1); 2, post treatment (1 week after the end of the intervention, week 8); and 3, follow-up (1 month after the end of the intervention, week 12). At each appointment an external assessor took both FHP and neck mobility measurements following the protocol described above.
A headache diary was kept throughout the study (12 weeks). Patients were required to register in the diary the days with headache, headache duration (in h/day) and the headache intensity on a 10-cm horizontal VAS (range: 0, no pain to 10, maximum pain) (22). At the end of the study the external assessor was given the headache diary and calculated the following variables: (i) headache intensity, calculated from the mean of the VAS of the days with headache; (ii) headache frequency, calculated by dividing the number of days with headache by the number of analysed weeks (days per week); and (iii) headache duration, calculated by dividing the sum of the total hours of headache by the number of days with headache (h/day). Pretreatment data of headache intensity, frequency and duration outcomes were obtained from the baseline period (first 4 weeks); post-treatment data were derived from the following 4 weeks, and follow-up data were calculated from the last 4 weeks of the evaluation protocol.
Statistical analysis
Data were analysed with the SPSS statistical package (version 13.0; SPSS Inc., Chicago, IL, USA). The Kolmogorov–Smirnov test demonstrated a normal distribution of quantitative data (P > 0.05). One-way analysis of variance (
Results
A total of 25 CTTH patients, eight men and 17 women, 17–72 years old (mean age 40 ± 17 years) were studied. Headache history ranged from 1 to 36 years (mean 9.1 ± 10.8 years). Baseline headache characteristics, i.e. intensity, frequency and duration, are shown in the first column of Table 1, together with neck mobility and posture measurements at the beginning of the study (pretreatment data).
Preintervention, post-intervention and follow-up data of neck mobility, forward head posture and headache clinical parameters
Values are expressed as mean ± SD.
FHP, Forward head posture (a lesser cranio-vertebral angle indicates a greater FHP); VAS, visual analogue scale (0 = no pain; 10 = maximum pain).
Neck mobility increased significantly after the physical therapy programme in all motions except for cervical flexion. This improvement was maintained 1 month after the end of the intervention (Table 1, Fig. 2). Head posture in both the sitting and standing positions also improved, but the changes in cranio-vertebral angle did not reach significance (Table 1). Finally, all headache clinical parameters showed a significant improvement compared with baseline levels in subsequent post-treatment and follow-up assessments (Table 1). Table 2 details the changes of all outcome measures during the study.
Changes in neck mobility throughout a physical therapy programme. 1, Pretreatment data; 2, post-treatment data; 3, follow-up data.
Changes of all outcome measures throughout the study
Values are expressed as mean ± SD; positive values indicate increase, whereas negative values indicate decrease.
P-values come from the
FHP, Forward head posture (a lesser cranio-vertebral angle indicates a greater FHP); VAS, visual analogue scale (0 = no pain; 10 = maximum pain).
Despite the trend towards clinical improvement of all outcome measures, our analysis revealed a significant correlation only between right cervical rotation and headache duration at both post-intervention (r = 0.5; P = 0.006) and follow-up (r = 0.4; P < 0.05) appointments. The remaining outcomes were not significantly correlated in any of the assessments (preintervention, post intervention, 1 month follow-up). Again, when we analysed the association between changes in FHP, changes in neck mobility and changes in headache parameters during each stage of the study (pre–post; post–follow-up; pre–follow-up), we found no significant correlation between these parameters.
Discussion
This study has demonstrated that FHP and neck mobility are not related to headache intensity, frequency or duration in patients suffering from CTTH. This basically agrees with a former study, where we found a significant correlation only between FHP and headache frequency, and none of the headache parameters was correlated with neck mobility (8). We have now monitored neck posture and motion as well as the clinical course of headache in a group of CTTH patients undergoing a physical therapy programme. Apart from a single association between right cervical rotation and headache duration after the treatment procedure, we found no significant correlation between FHP, neck mobility and headache parameters at any phase (preintervention, post intervention or 1-month follow-up). Moreover, changes in headache parameters throughout the study (pre–post; post–follow-up and pre–follow-up) were not correlated with either changes of FHP or changes of neck mobility.
The fact that head posture and neck motion were not correlated with these clinical variables reflecting the severity of headache does not necessarily mean that TTH patients are free of neck musculoskeletal abnormalities. In fact, we have previously found that a group of CTTH patients showed greater FHP and lesser neck mobility than a group of healthy controls (8). However, we must bear in mind that Zwart found no differences in neck mobility between TTH patients and controls (7). We can state that our patients showed a reduction in the range of motion in the neck, but it is uncertain whether this is consistent with TTH. All our patients presented with chronic headache, whereas the episodic and chronic patterns of headache were not distinguished in Zwart's study. There might be some differences in neck mobility between the chronic and the episodic forms of TTH. However, this cannot be verified with the data available.
It seems that posture and mobility dysfunctions may be usual features of TTH, although they appear not to play a crucial role in the genesis or maintenance of headache. TTH is considered to be a multifactorial disorder, in which both peripheral and central mechanisms are probably involved (23, 24). FHP and restricted neck mobility might be related in some way to peripheral factors contributing to headache, such as myofascial pain sensitivity, but these peripheral factors may also be modulated by the sensitization of central pain pathways. Alternatively, posture and mobility dysfunctions might be a consequence rather than a causative factor of headache. FHP may merely represent an antalgic posture, while restricted neck mobility could be a result of FHP, head pain or both. As yet, the implications of neck abnormalities in TTH have not been elucidated.
Although no correlation was found between the outcome measures, we should recognize that our CTTH patients experienced a significant improvement in both neck mobility and clinical headache parameters after the physical therapy programme. Moreover, this improvement was maintained 1 month after the end of the intervention. In contrast, FHP did not change significantly throughout the study. This was in agreement with the results of Jull et al., who reported no changes in the cranio-vertebral angle following exercise and manipulative therapy in patients suffering from cervicogenic headache (25). The chronic and stable nature of headache symptoms prior to the beginning of the study suggests that the observed changes were associated with the intervention, rather than spontaneous remission. Nonetheless, the aim of our study was not to assess the effectiveness of physical therapy in TTH. There are as yet only a few randomized controlled trials testing the effectiveness of manual therapies in the management of TTH (17). Further well-designed clinical trials are required before manual therapies can be sufficiently validated for the treatment of patients with TTH.
This is the first study to analyse the relationship between FHP, neck mobility and clinical features after a physical therapy programme for TTH. However, it has some limitations. First, as previously stated, it was not designed as a randomized controlled trial. Accordingly, we cannot assume a cause and effect relationship between the physical therapy programme and clinical changes. A stronger design should include a control group receiving another type of treatment or a placebo intervention. Second, only patients with CTTH were included. Hence, our results cannot be extrapolated to the episodic form of TTH or to other headache disorders. It would be of interest to repeat the same procedure with patients suffering from other conditions. The third limitation was the sample size. To determine possible clinical implications of neck abnormalities in TTH, our findings must be confirmed in a large number of subjects.
In conclusion, FHP and neck mobility appear not to be related to headache intensity, duration or frequency in patients suffering from CTTH. Likewise, changes of head posture and neck motion are not significantly related to changes in headache parameters in patients with CTTH undergoing a physical therapy programme. Other factors could be more directly involved in the origin and maintenance of TTH.